Alternating current electromagnet



Nov. 13, 1934. c. T. EVANS 1,980,393

' ALTERNATING CURRENT ELECTROMAGNET Filed Feb. 8, 1934 Patented Nov. 13, 1934 PATENT: OFFICE ALTERNATING CURRENT ELECTROMAGNET Clarence T. Evans, Wauwatosa, Wis., assignor to Cutler-Hammer, Inc., Milwaukee, Wis., a corporation of Delaware Application February 8, 1934, Serial No. 710,222

3 Claims.

This invention relates to alternating current electromagnets.

Such magnets for well known reasons are commonly provided with laminated cores and armatures comprising magnetic material, and in service the coacting armature and core faces through wear cause chattering or even more serious trouble, the magnetic materials available lacking a high degree of resistance to wear. Accordingly it has long been desired to improve such laminated cores and armatures to minimize the wear on their coacting faces, but heretofore it has not been found possible to materially reduce wear without sacrifice of efficiency or some desired 5 characteristic.

The present inventionhas as its main object provision of a construction suitable for both cores and armatures which will give high wear resistance of the coacting faces without sacrifice of efliciency or any desired operating characterlstic.

Another object is to obtain the aforementioned high resistance to wear at little additional expense.

Other objects and advantages of the invention will hereinafter appear. I

According to the present invention it is proposed to build into the laminated structure either in solid or laminated form non-magnetic mate- 3 rial having a high resistance to wear and to utilize for such purpose the known steel alloy having about 18% chromium and 8% nickel, such .alloy being commonly called ,188 steel. Further it is proposed to build in pieces of such nonmagnetic material for exposure thereof preferably at boundaries of the working faces and at intermediate points and to machine such pieces and the magnetic laminae after assembly to provide coacting faces capable of intimate contact.

On test of an electromagnet provided with a core and armature so constructed it was found to have a life of about nine million operations, whereas the same magnet provided with the usual laminated core and armature would only have a life of about five million operations. The electromagnet thus tested had the aforementioned steel alloy built into the core and armature at the center of each to a width about A" and it was found that upon increasing the steel alloy part to a width of A" the life of the electromagnet was increased to nineteen million operations. These tests moreover demonstrated, as has subsequent commercial use of electromagnets constructed as herein proposed, that increased resistance to wear may thus be obtained without sacrifice as aforestated.

The accompanying drawing illustrates an electromagnetic switch embodying the invention in a preferred form, and the same will now be described, it being understood that the invention may be embodied in other forms falling within the scope of the appended claims.

In the drawing,

Figure 1 is a front elevational view of the switch;

Fig. 2 is a side elevational view of the switch, and

Fig. 3 is a view looking down on the electromagnet, the winding of which is shown in section to disclose its cores.

Referring to the switch illustrated, the same is in general of conventional form comprising a switch arm 1 mounted on a shaft 2 supported by a panel 3 and a magnetic armature 4 also mounted on said shaft or a separate aligned shaft and having an extension 5 operatively connected to an extension 6 of the switch arm, an electromagnetic winding 8 and a magnetic frame or core member 9 which supports said winding. The core member 9 is supported on shaft 2 and the panel carries a bolt 10 passing loosely through a plate 11 carried by extensions 12 of the core at the upper end of the latter. The bolt 10 is adjusted to permit a slight rocking of the core whereby 65 the latter may yield when struck by the armature while a cushioning spring 13 is interposed between the core and the panel 3.

Considering now the construction of the core and armature illustrated each comprises laminae a of magnetic material and elements b preferably comprising the aforementioned non-magnetic steel alloy in the form of plates. The plates are preferably arranged as illustrated whereby certain form side plates for the core and armature, the remainder being located between groups of the magnetic lamina, such groups preferably containing the same number of lamina. As will be understood, the laminae may be of any preferred shape while the non-magnetic plates may be of like or different shape. In the structure illustrated the plates with certain exceptions are of the same shape as the laminae and of like dimensions, being securedtogether in assembled relations by suitable rivets 14 and 15. As illustrated certain of the central plates of the armature are extended downwardly to afford a bearing to receive shaft 2 and to form extension 5, while certain of the central plates of the core are extended downwardly to form bearings to receive shaft 2,

and upwardly to provide the extensions 12 carrying plate 11.

The laminae and plates are so assembled that the edges thereof forming the coacting faces of the core and armature are substantially flush in the core and in the armature and then such faces are preferably machined for intimate contact when brought together, the aforementioned steel alloy being readily machinable.

As will be understood, either the core or armature may be slotted to receive a shading coil of any of the numerous well known forms.

What I claim as new and desire to secure by Letters Patent is:

' 1. An electromagnet having its core and armature built up of lamina: of magnetic material and elements of steel alloy having about 18 per cent chromium and about 8 per cent nickel, the coacting faces of said core and armature comprising flush edges of said laminae and elements and said lamina: and elements being arranged for contacting of the steel alloy elements of said coacting faces when such faces are brought together.

2. An electromagnet having its core and armature built up of lamina: of magnetic material and elements of steel alloy having about 18 per cent chromium and about 8 per cent nickel, said lamina: and elements having flush edges forming the coacting faces of said core and armature and said lamina: and elements being arranged to-provide steel alloy surfaces at opposite sides of each of said coacting faces and also substantially centrally of each to contact with the corresponding elements of the other coacting face when said faces are brought together.

3. An electromagnet having its core and armature built up of laminae of magnetic material and non-magnetic wear resisting plates, the coacting faces of said core and armature comprising flush edges of said lamina: and plates, certain of said plates forming side plates for said core and armature and others being arranged between groups of said laminae, the plates of said core and armature being in a relation to contact when the cooperating faces of the core and armature are brought together.

CLARENCE T. EVANS. 

